Fix 'ned' typo in doc comment

Patch by Jasper Neumann!

llvm-svn: 199007
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
index 835f643..d67c846 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
@@ -627,7 +627,7 @@
                                                 bool useVoidTy = false);
 
   /// UpdateSplitBlock - When an MBB was split during scheduling, update the
-  /// references that ned to refer to the last resulting block.
+  /// references that need to refer to the last resulting block.
   void UpdateSplitBlock(MachineBasicBlock *First, MachineBasicBlock *Last);
 
 private: